The invention relates to novel partial esters of polyphosphoric acids such as diphosphoric acid. Previously known partial esters have not been stable due to hydrolytic decomposition resulting in formation of monophosphoric acid esters.
In U.S. Pat. Nos. 2,866,680 and 2,947,774 the formation of certain alkyl esters of di- and polyphosphates are described. The compounds were unstable and decomposed within hours or at best after a few days if refrigerated.
In U.S. Pat. No. 3,004,056, surface-active monophosphates are formed by gradual addition of solid P.sub.2 O.sub.5 to an excess of polyoxyalkylene ether with vigorous agitation. The specification teaches that addition of the hydroxyl compound to the P.sub.2 O.sub.5 is inadvisable since a tar is formed thereby and the reaction will not proceed to completion.